1. Field of the Invention
The present invention relates generally to a magnetic disk drive, and more particularly to a connection structure for supplying a write signal to a magnetic head or retrieving a signal read by the magnetic head from the magnetic disk drive to external equipment.
2. Description of the Related Art
In recent years, size reduction and thickness reduction have been advanced in a magnetic disk drive as a kind of external storage for a computer. Further, low power consumption in such a magnetic disk drive is also desired. In addition, an improvement in recording density of a magnetic disk is also demanded to obtain a large storage capacity, and the number of disks to be mounted in the disk drive is accordingly increasing.
In a magnetic disk drive for a computer, a contact start and stop (CSS) system defining the relation between a head and a disk is generally adopted. In this system, while the disk is being rotated at a high speed, a head flying force generated by an air flow due to high-speed rotation of the disk balances a pressing force of a suspension pressing the head on the disk, so that the head is kept at a microscopic flying height from the disk. When the rotation of the disk is stopped, the head is moved to a landing zone on the disk and comes to contact with the disk at this zone. In the rest condition of the disk, the head and the disk remain in contact with each other.
Conventionally, lead wires mounted on the suspension are used to supply a write signal to the head or take a signal read by the head out of the magnetic disk drive. However, as downsizing of the magnetic disk drive proceeds, the structure of the suspension to be adopted is being shifted from the above type that the lead wires are mounted to another type that a conductor pattern connected to the head is formed integrally on the surface of the suspension.
In a conventional magnetic disk drive adopting such a suspension with a conductor pattern, there is provided inside the magnetic disk drive a main flexible printed circuit sheet (which will be hereinafter referred to as a main FPC) for leading wiring to a printed circuit board provided outside the magnetic disk drive. Terminals provided at a base end portion of the suspension are connected through lead wires to terminals of the main FPC. The main FPC is fixed at its one end portion to an actuator arm by bonding or screwing. Accordingly, the lead wires are installed along a side surface of the actuator arm.
A magnetoresistive head (MR head) has been developed as a head in a recent magnetic disk drive. The MR head has an inductive element to be used in writing data and a magnetoresistive element (MR element) to be used in reading data. Accordingly, the number of signal lines is four in using the MR head as compared with a conventional general head requiring two signal lines. Such an increase in number of signal lines causes an increase in number of wiring assembly steps double that in the general head in connecting the terminals of the suspension through the lead wires to the terminals of the main FPC.
Further, since the number of the terminals is also increased, a double space for installing the terminals of the suspension and the terminals of the main FPC becomes necessary. However, in the recent magnetic disk drive designed to reduce its size and thickness, sufficient space for installation of the terminals is difficult to ensure. That is, the terminal installation space is small and the distance between the adjacent terminals must be reduced.
For these reasons, it is undesirable to use the lead wires for the connection between the terminals of the suspension and the terminals of the main FPC. In this respect, there has been proposed a technique of connecting the terminals of the suspension and the terminals of the main FPC by using an interconnection flexible printed circuit sheet (which will be hereinafter referred to as an interconnection FPC). In this prior art, the interconnection FPC is attached to the side surface of the actuator arm to connect a conductor pattern formed on the suspension and a conductor pattern formed on the main FPC.
The advance of size reduction and thickness reduction of the recent magnetic disk drive as described above causes a reduction in thickness of the actuator arm. Further, the use of the MR head causes an increase in number of signal lines to be enclosed in the interconnection FPC. Accordingly, in the above prior art method where the interconnection FPC is attached to the side surface of the actuator arm, the width of the interconnection FPC is decreased with a decrease in thickness of the actuator arm to cause a problem such that it is difficult to ensure a necessary number of signal lines in the interconnection FPC and the pattern width of each signal line is reduced.